Problem: According to the World Health Organization, more than 35 million people worldwide suffer from dementia. Though we still lack a lot of understanding about dementia—where it comes from and how to stop it—we do know that mild cognitive impairment, or MCI, is a risk factor for dementia, and scientists think it may be a stage where we can successfully intervene before it develops further. Previous research has shown that the brain benefits from aerobic exercise, and in a new study published in the British Journal of Sports Medicine aims to see if exercise could be the intervention we’ve been looking for.

Methodology: Researchers from Canada and the Netherlands did a 26-week study on 86 women who were between 70 and 80 years old. The study focused only on women to avoid potential gender differences in how the brain responds to exercise. The participants were assigned to an aerobic training, resistance training, or balance and tone training regimen (this last one was the control group), and performed their respective exercises twice per week.

Before and after the 26 weeks of exercise, the researchers measured the volume of participants’ hippocampuses (the region of the brain associated with memory, and whose atrophy is associated with Alzheimer’s Disease) as well as their performance on a verbal learning test that asked them to recall words spoken aloud to them.

Results: The group that did aerobic exercise had significantly increased hippocampal volume at the end of the 26 weeks, compared with the control group. The resistance training group did not see this effect. However, the increase in hippocampal volume was associated with somewhat worse performance on the verbal learning test. The researchers called this latter finding “unexpected.”

Implications: Aerobic exercise may stimulate neurogenesis (the growth of new neurons), the researchers posit, and this may be why it led to increased hippocampal volume. Though the participants’ performance on the verbal learning test was unexpectedly lower when their brains had grown, the study suggests that it may be that greater brain volume doesn’t necessarily result in better cognitive performance. There could be other factors at play, such as the degeneration in older brains of signal-transmitting white matter.

Though more research is, as always, needed, this study shows that one of the risk factors for dementia—decreased hippocampal volume, can be effectively combatted with exercise, beefing up not just muscles, but brains.